Resistor non-linearity is a source of non-linearity in data converter circuits. A data converter circuit with an ideal resistor exhibits linear operation. However, resistor non-linearity results in data converter non-linearity.
The following expression represents linear gain within an ideal two terminal resistor,V(I)=IR  (1)
In practice, resistor nonlinearity occurs due to self-heating of the resistor according to a nonzero temperature coefficient of resistance. As a resistor carries more current it dissipates power and heats up, and its resistance changes, which creates a nonlinear relationship between voltage and current. In general, the most linear type of resistor is the thin-film resistor (TFR). However, even TFRs exhibit a nonlinearity. Integrated thin film resistors in silicon dioxide (SiO2), for example, are particularly prone to heating. SiO2 has a very low thermal conductivity, around 100× lower than silicon, and around 200× lower than most metals. The low thermal conductivity slows heat dissipation resulting in heat-up and nonlinearity according to temperature coefficient of resistance.